System And Method To Vaporize A Process Stream By Mixing The Stream With A Heating Medium

ABSTRACT

A system and method to vaporize a process or feed water stream does so in a liquid pool zone of a vessel as the stream comes into contact with a heating medium that is less volatile than the process stream. To keep the pool hot, the heating medium can be recirculated through a heater of a pump-around loop or a heater can be placed in the liquid pool. As the process stream is vaporized, any solids present in the process stream come out of the process stream and move into the heating medium. These solids may be further removed from the heating medium in the pool or in the pump-around loop. The vaporized process stream can be further condensed. Any heat recovered can be used to pre-heat the process stream or used in the pump around loop&#39;s heater in case of mechanical vapor recovery.

BACKGROUND

This disclosure is in the field of vaporization and desalinationprocesses such as, but not limited to, those used in mono ethyleneglycol (“MEG”) reclamation applications, seawater desalinationapplications, total dissolved solids reduction applications, and generalprocess water treatment for reuse or disposal.

Current vaporization and desalination processes are complicated,expensive, and typically require extensive pretreatment. In some cases,the cost of pretreatment exceeds the cost of the actual vaporization ordesalination processes. U.S. Pat. No. 8,652,304 B2 (“Nazzer”) disclosesa method of extracting dissolved or undissolved solids from a mixture ofwater and a process liquid or stream. The mixture is introduced into amixing zone within or upstream of a separation vessel where it isfurther mixed with a recycle fluid extracted from a liquid pool zone ofthe separator vessel and pumped through a heat exchanger.

Vaporization occurs in this mixing zone (where more than 99% of thevolatile components of the feed stream are vaporized). The resultingstream is then transferred to the separator vessel in which the vapor isseparated, with the solid and liquid components falling into the liquidpool zone of the separator vessel. A portion of these solids and liquidsthat bond to these solids then passes through a stripping zone of theseparator vessel. Water residing within the stripping zone displaces theliquids bound to the solids and an aqueous waste stream with dissolvedor nondissolved solids results.

Because this method requires a mixing zone for vaporization outside ofthe liquid pool, the required equipment is difficult to design and proneto scaling and plugging. The method also does not allow for vaporizationwithin the liquid pool and requires the heating medium—i.e., the recyclefluid, immiscible with the process stream and lighter than the water inthe stripping zone—to be recycled at a rate of at least ten times thatof the process feed rate. This high recycle rate is required because themethod must limit the temperature difference between the recycle fluidand the process stream in order to avoid thermal degradation effects.Additionally, the method does not allow for partial vaporization with ablowdown.

Last, the method requires a stripping zone for solids removal. Astripping zone is prone to corrosion because of unvaporized (solids)components from the process stream. The stripping zone also presentssafety concerns due to the risk of higher temperature oil contactingwater. To reduce the safety concern, the oil must be cooled before ittouches the water in the stripping zone, but cooling the oil increasesits viscosity and ineffective solids separation results.

SUMMARY

The present disclosure simplifies the system and method of vaporizing aprocess stream and reduces the cost of doing so.

Vaporization in a mixing zone outside of the liquid pool does not occurin embodiments of the system and method, nor do the system and methodhave a stripping zone for solids removal. The system and method is notlimited to a light heating medium relative to the process stream and, insome embodiments, does not have an immiscible heating medium. Anypre-mixing of the process stream and heating medium may be done at alevel below that required for vaporization of the process stream.Pre-mixing may also be done to provide a relatively small amount ofvaporization to enhance the pre-mixing and accelerate the fluid when itenters the liquid pool.

Embodiments of the system and method may disperse the process or feedwater stream into a liquid pool containing a hot heating medium that isless volatile than the process or feed water stream. To keep the poolhot, the heating medium can be recirculated through a heater in apump-around loop. Alternatively or additionally, a heater can be placedin the liquid pool.

As the process stream is vaporized, any dissolved or undissolved solidspresent in the process or feed water stream come out of the stream andmove into the heating medium. The solids that move into the heatingmedium may be further removed from the heating medium within the vesselor in a separator located in the pump-around loop. If the removal ofsolids and unvaporized liquids occurs in the vessel, the vessel shouldinclude internals of a kind known in the art to separate the unvaporizedportion of the process or feed water stream from the heating medium. Ifthe removal of the solids and unvaporized liquids occurs in a separatorin the pump-around loop, the separator can be a hydrocyclone,centrifuge, particulate filter, settling tank, or some other piece ofseparation device equivalent to these.

In some embodiments, the vaporized process or water stream can becondensed or compressed and condensed. Heat recovered during condensingcan be used to pre-heat the process stream prior to its introductioninto the liquid pool, or to heat the heating medium in the pump aroundloop.

The system and method can be used in applications such as but notlimited to MEG reclamation; seawater desalination; steam generation;total dissolved solids (“TDS”) reduction for produced water, desalterwash water, fracking flowback water, and amine reclamation. Unlike priorart systems and methods, there is no requirement for pretreatment of theprocess or feed water stream or low temperature differentials betweenthe vaporization temperature of the stream and heating medium (e.g.,limited to 10° C. above the vaporization temperature due to the risk ofscaling in the heat exchanger in the pump-around loop).

The embodiments of this disclosure may simplify the system and method tovaporize a process stream; reduce the costs associated with prior artvaporization systems and processes; generate a much smaller dischargestream relative to prior art systems and methods; and eliminate thedesign and operational challenges presented by mixing zones locatedoutside of the liquid pool zone of the vessel and stripping zones forsolids removal. The disclosure also eliminates the need for lightheating mediums relative to the process or feed water stream, andeliminates the need for immiscible heating mediums. The disclosure alsodoes not require the low temperature differential between the stream andheating medium or recycle rates of at least 10 times greater than thatof the process feed.

The disclosure also reduces, and potentially eliminates, pretreatmentfor the process or feed water stream while at the same time minimizingor eliminating scaling and fouling of equipment. Any pre-mixing of theprocess or feed water stream and the heating medium that occurs outsideof the liquid pool zone may be done at a level below that at which thestream vaporizes. Pre-mixing may also be done to provide a relativelysmall amount of vaporization to enhance the pre-mixing and acceleratethe fluid when it enters the liquid pool.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the above recited features can be understood in detail, a moreparticular description may be had by reference to embodiments, some ofwhich are illustrated in the appended drawings, wherein like referencenumerals denote like elements. It is to be noted, however, that theappended drawings illustrate various embodiments and are therefore notto be considered limiting of its scope, and may admit to other equallyeffective embodiments.

FIG. 1 is a schematic of an embodiment of a system and method tovaporize a process or feed water stream. A process stream havingdissolved or undissolved solids is routed to a heating medium pool of avessel. As the process stream vaporizes, the solids in the processstream, both dissolved and undissolved, come out of the process streamand move into the heating medium. The vessel includes internals to allowthe separation of the solids from the heating medium and remove thesolids out of the vessel. A pump-around loop recycles and heats theheating medium. If any pre-mixing of the process stream and heatingmedium occurs outside of the liquid pool (see FIG. 6), the pre-mixingmay be at a level below that at which vaporization occurs. Pre-mixingmay also be done to provide a relatively small amount of vaporization toenhance the pre-mixing and accelerate the fluid when it enters theliquid pool.

FIG. 2 is an embodiment of the system and method. The pump-around loopincludes a separator for removing solids. The separator can be ahydrocyclone, centrifuge, particulate filter, settling tank, or someother piece of separation device equivalent to these.

FIG. 3 is an embodiment of the system and method. The vaporized processstream is partially condensed.

FIG. 4 is an embodiment of the system and method. Heat recovered fromcondensing is used to pre-heat the process stream prior to it beingrouted to the heating medium pool of the vessel.

FIG. 5 is an embodiment of the system and method. The vaporized processstream is compressed and this pressurized process stream is condensed inthe pump-around loop to help heat the heating medium being recycled inthe loop.

FIG. 6 is an embodiment of the system and method. Pre-mixing of theprocess stream and heating medium occurs outside of the liquid pool zoneof the vessel but at a level below that needed for vaporization. Thepump-around loop could include a separator for removing solids (see e.g.FIG. 2). Pre-mixing may also be done to provide a relatively smallamount of vaporization to enhance the pre-mixing and accelerate thefluid when it enters the liquid pool.

ELEMENTS AND NUMBERING USED IN THE DRAWINGS AND DETAILED DESCRIPTION

-   -   10 System or method    -   15 Process stream    -   15A Process stream prior to preheating    -   15B Pre-heated process stream    -   17 Mixer within or outside of 20    -   20 Vessel    -   21 Liquid pool zone    -   23 Heating medium    -   24 Interior volume    -   25 Unvaporized (dissolved or undissolved solids) portion of 15    -   27 Vapor separation zone    -   29 Vaporized volatile components of 15    -   30 Vaporized process stream    -   35 Removed heating medium stream or mixture (heating medium 23        and unvaporized portion 25)    -   40 Pump-around loop    -   41 Heater    -   45 Heated recycle stream substantially unvaporized portion-free        or with a reduced unvaporized portion 25 (relative to removed        stream or mixture 35)    -   47 Separator or separator device (solids removal device such as        a hydrocyclone, centrifuge, particulate filter, settling tank or        their equivalents)    -   50 Heating medium stream substantially unvaporized portion-free        or with a reduced unvaporized portion 25 (relative to stream or        mixture 35)    -   60 Condenser    -   65 Partially or totally condensed process stream    -   70 Compressor    -   75 Pressurized stream

DETAILED DESCRIPTION

In the following description, numerous details are set forth to providean understanding of some embodiments of the present disclosure. However,it will be understood by those of ordinary skill in the art that thesystem and/or methodology may be practiced without these details andthat numerous variations or modifications from the described embodimentsmay be possible.

In the specification and appended claims, the terms “connect”,“connection”, “connected”, “in connection with”, and “connecting” areused to mean “in direct connect with” or “in connection with via one ormore elements”; and the term “set” is used to mean “one element” or“more than one element”. Further, the terms “couple”, “coupling”,“coupled”, “coupled together”, and “coupled with” are used to mean“directly coupled together” or “coupled together via one or moreelements”. As used herein, the terms “up” and “down”, “upper” and“lower”, “upwardly” and “downwardly”, “upstream” and “downstream”,“above” and “below”, and other like terms indicated relative positionsabove or below a given point or element and are used in this descriptionto more clearly describe some embodiments of the disclosure.

Embodiments of a system and method to vaporize volatile components of aprocess or feed water stream achieve vaporization of those components inthe liquid pool zone of the vessel when the stream contacts a heatingmedium residing in the liquid pool zone. The vessel is arranged todirectly receive the process or feed water stream, thereby eliminatingpre-treatment between it and the upstream process providing the stream.A pump-around loop heats a portion of the heating medium and recyclesthis heated portion back to the vessel.

The heating medium—which can be miscible or substantially immisciblewith the stream and can be lighter or heavier than the stream—ismaintained at an operating temperature required for the desiredvaporization effects. Pre-mixing may also be done to provide arelatively small amount of vaporization to enhance the pre-mixing andaccelerate the fluid when it enters the liquid pool. The vessel can alsomake use of blowdown to remove solids formed during the vaporization ofthe process or feed water stream. A separate vessel located in thepump-around loop can be used for liquids-solids separation.

The different arrangements of the system and method 10 as shown in FIGS.1 to 6 route a process or feed water stream 15 into a vessel 20 whoseinterior volume 24 is defined by a liquid pool zone 21 and a vaporseparation zone 27. A heating medium 23 resides within the liquid poolzone 21 and this heating medium 23 is used to vaporize the volatilecomponents 29 of the process stream 15. Mixing of the process stream 15and heating medium 23 occurs naturally within the liquid pool zone 21 asthe process stream 15 enters the zone 21.

The now vaporized portions 29 of the process stream 15 migrate to avapor separation zone 27 of the vessel 20 and are removed as a vaporizedprocess stream 30. The vaporized process stream 30 can be routed to acondenser 60, as shown in FIGS. 3 and 4, to produce a partiallycondensed process stream 65. Heat from the condenser 60 can be recoveredand used to raise the temperature of the process stream 15A so thatstream 15 flows into the liquid pool zone 21 as a pre-heated processstream 15B.

The vaporized process stream 30 can also be routed to a compressor 70,as shown in FIG. 5. The now pressurized process stream 75 is condensedin the pump-around loop 40, with heat being recovered and used to heatthe recycle stream 45.

As the volatile components 29 of the process stream 15 vaporize, theunvaporized (dissolved and undissolved solids) portion 25 of the processstream 15 moves into the liquid pool zone 21 along with the heatingmedium 23. The solids 25 can be separated from the heating medium 23either within the vessel 20 or within a separator 47 located in thepump-around loop 40. No stripping zone is used for solids 25 removal.

The separator 47 used in the pump-around loop 40 can be any separatorsuitable, including but not limited to a hydrocyclone, centrifuge,particulate filter, settling tank, or some other piece of separationdevice equivalent to these. A heating medium stream 50 with reducedamounts of, or without, unvaporized portion 25 exits the separator 47and passes through the heater 41. The heated recycle stream 45 thenrecycles back to the liquid pool zone 21 of the vessel 20. The heatedrecycle stream 45 may include some portion of the dissolved orundissolved solids 25 of the process stream 15.

The heating medium 23 is maintained at an operating temperature thatprovides the desired vaporization effects. The heating medium 23 can beany heating medium depending on the make-up of process or feed waterstream 15 and application-specific requirements. For example, theheating medium 23 could be one that one that is lighter than, heavierthan, or the same density as the process stream 15. The heating medium23 could also be one that forms either a homogeneous or heterogeneousmixture with the process stream 15. However, the heating medium 23 isless volatile than the volatile components 29 of the process stream 15.

To keep the heating medium 23 at the selected operating temperature, aheater (not shown) can be placed in the liquid pool zone 21.Alternatively or additionally, a removed stream 35 of the heating medium23, which may include solids 25 residing within the liquid pool zone 21,can be removed from the vessel 20 and routed to the pump-around loop 40and its heater 41. A heated recycle stream 45 that may include dissolvedand undissolved solids 25 then recycles back to the liquid pool zone 21.

An embodiment of a method to vaporize a process stream includes:

-   -   routing the process (or feed water) stream 15 directly into the        liquid pool zone 21 of the vessel 20 where it becomes mixed with        a heating medium 23 that is less volatile than the process        stream 15 and maintained at an operating temperature determined        by vaporization requirements to vaporize a volatile components        portion 29 of the process stream 15; and    -   removing the vaporized portion 29 of the process stream 15 from        the vapor separation zone 27 of the vessel 20 as a vaporized        process stream 30.

Prior to the process stream 15 entering the liquid pool zone 21 theremay be no pre-treatment of the stream 15 as it exits the upstreamprocess providing the stream 15 and there may be no mixing of theprocess stream 15 with the heating medium 23. Pretreatment meanstreatment such as but not limited to chemical dosing, filtration usingselectively permeable membranes, separators, or the use of ion exchange,deaerators or blowdown prior to the process stream 15 entering vessel 20(or some combination of the above pretreatment methods). (Coarsestraining of a kind known in the art and typically done ahead ofpretreatment might be used if the feed is taken directly from a naturalbody of water or from a source with excessive undissolved solids.) Ifany pre-mixing of the process stream 15 and heating medium 23 occursoutside of the liquid pool zone 21 (see e.g. mixer 17 in FIG. 6), thepre-mixing may be done at a level below that at which vaporizationoccurs. Therefore, vaporization of the process stream 15 occurs withinthe liquid pool zone 21 of the vessel 20.

Pre-mixing may also be done to provide a relatively small amount ofvaporization to enhance the pre-mixing and accelerate the fluid 15, 45when it enters the liquid pool 21. The amount of vaporization thatoccurs in pre-mixing may be less than that which occurs in the liquidpool. For example, during normal (non-turndown) operations no more thanabout 20% or about 5% of the volatile components in the stream 15 mayvaporize during pre-mixing. If the amount of vaporization does exceedthat of the liquid pool, during normal operations vaporization duringpre-mixing should not exceed about 80% or about 90% of the volatilecomponents. Limiting the amount of vaporization during pre-mixing helpsavoid the design challenges and scaling and plugging problems associatedwith the mixing zone of the prior art (see Background).

The heating medium 23 and process stream 15 can form a heterogenous orhomogenous mixture when residing within the liquid pool zone 21.Additionally, the density of the heating medium 23 can be greater than,less than, or equal to that of the process stream 15.

The method can also include removing a portion 35 of the heating medium23 residing in the liquid pool zone 21 of the vessel 20; raising atemperature of the removed portion or stream 35 to produce a heatedrecycle stream 45; and routing the heated recycle stream 45 back to theliquid pool zone 21. The removed stream 35 can also be routed to aseparator 47 to produce a heating medium stream 50 substantiallyunvaporized portion-free or with a reduced unvaporized portion 25. Onceheated by heater 41, it can be returned to the liquid pool zone 21 asthe heated recycled stream 45 (also substantially unvaporizedportion-free or with a reduced unvaporized portion 25).

Last, the method can also include condensing at least a portion of thevaporized process stream 30. Heat recovered from the condenser 60 can beused as pre-heating to raise the temperature of at least a portion ofthe process stream 15A prior to the process stream 15B directly enteringthe liquid pool zone 21 of the vessel 20. Alternatively or additionally,the method can include compressing at least a portion of the vaporizedprocess steam 30. The pressurized stream 75 is then condensed in thepump-around loop 40 and used to raise the temperature of the recyclestream 45.

An embodiment of a system to vaporize a process stream includes a vessel20 arranged to contact a process or feed water stream 15 exiting anupstream process and route the process stream 15 into a heating medium23 residing within the liquid pool zone 21 of the vessel 20. Theinterior volume 24 of the vessel 20 does not include a stripping zonefor solids 25 removal. The heating medium 23 is less volatile than theprocess stream 15 and maintained at an operating temperature determinedby vaporization requirements. The vaporized volatile components 29 ofthe process stream 15 migrate to the vapor separation zone 27 of thevessel 20.

A pump-around loop 40 is arranged to receive a portion 35 of the mixedheating medium 23 along with the non-volatile (dissolved andundissolved) components 25 of the process stream 15 that have moved intothe heating medium 23 and then return the portion 35 back to the liquidpool zone 21 as a heated recycle stream 45. The pump-around loop 40 ofthe system can also include a heater 41 as well as a separator 47arranged upstream of the heater 41 so that a substantially solids-freeor reduced solids stream 45 is being returned to the vessel 20.

Prior to contacting the heating medium 23, the process stream 15 may notbe mixed with the heating medium 23 outside of the liquid pool zone 21of the vessel 20. If any pre-mixing of the stream 15 and heating medium23 occurs, the mixing may be at a level below that required forvaporization of the volatile components 29. Pre-mixing may also be doneto provide a relatively small amount of vaporization to enhance thepre-mixing and accelerate the fluid when it enters the liquid pool 21.

The system can also include a condenser 60 arranged to receive at leasta portion of a vaporized process stream 30 exiting the vapor separationzone 27 of the vessel 20. Heat recovered from the condenser 60 can alsoserve as a pre-heater to raises the temperature of the process stream15A prior to the process stream 15B directly entering the liquid poolzone 21 of the vessel 20.

The system may include a compressor 70 arranged to receive at least aportion of the vaporized process stream 30. Heat recovered fromcondensing the pressurized stream 75 can be used in the pump-around loop40 to raise the temperature of the recycle stream 45.

Although the preceding description has been described herein withreference to particular means, materials, and embodiments, it is notintended to be limited to the particulars disclosed herein; rather, itextends to all functionally equivalent structures, methods, and uses,such as are within the scope of the appended claims.

What is claimed:
 1. A method to vaporize a process stream, the methodcomprising: routing the process stream into a liquid pool zone of avessel, the liquid pool zone including a heating medium, the heatingmedium being less volatile than the process stream and maintained at anoperating temperature determined by vaporization requirements;vaporizing volatile components of the process stream due to contact withthe heating medium in the liquid pool zone; and removing a vaporizedportion of the process stream from a vapor separation zone of the vesselas a vaporized process stream; wherein the interior volume of the vesseldoes not include a stripping zone for solids removal.
 2. A methodaccording to claim 1 further comprising pre-mixing the process streamand the heating medium outside of the liquid pool zone of the vessel. 3.A method according to claim 2 wherein during pre-mixing no vaporizationof the volatile components of the process stream occurs.
 4. A methodaccording to claim 2 wherein during pre-mixing no more than about 90% ofthe volatile components of the process stream vaporize.
 5. A methodaccording to claim 1 further comprising separating and removing at leastsome of the unvaporized portion from the vessel directly as blowdown. 6.A method according to claim 1 further comprising: removing a portion ofthe heating medium residing in the liquid pool zone of the vessel;raising a temperature of the removed portion to produce a heated recyclestream; and routing the heated recycle stream back to the liquid poolzone.
 7. A method according to claim 6 wherein the removed portion ofthe heating medium is a mixture of heating medium and at least some ofthe non-volatile components of the process stream.
 8. A method accordingto claim 7 further comprising separating and removing at least some ofthe non-volatile components prior to raising the temperature.
 9. Amethod according to claim 1 further comprising condensing at least aportion of the vaporized process stream.
 10. A method according to claim1 further comprising compressing at least a portion of the vaporizedprocess steam.
 11. A method according to claim 1 further comprisingraising a temperature of at least a portion of the process stream priorto the process stream directly entering the liquid pool zone of thevessel.
 12. A method according to claim 1 wherein the process stream ishomogenously dispersed in the heating medium.
 13. A method according toclaim 1 wherein a density of the heating medium is greater than that ofthe process stream.
 14. A method according to claim 1 wherein theprocess stream includes water.
 15. A system to vaporize a processstream, the system comprising: a vessel arranged to contact the processstream and route the process stream into a liquid pool zone of thevessel, the liquid pool zone including a heating medium less volatilethan the process stream and maintained at an operating temperaturedetermined by vaporization requirements; and a pump-around loop arrangedto receive a portion of the heating medium residing in the liquid poolzone and return the portion back to the liquid pool zone; wherein whenthe process stream is contacted by the heating medium in the liquid poolzone volatile components of the process stream vaporize and migrate to avapor separation zone of the vessel; wherein the vessel does not includea stripping zone for solids removal.
 16. A system according to claim 15further comprising a mixer located outside of the liquid pool zone ofthe vessel and arranged to mix the process stream and the portion of theheating medium being returned to the vessel.
 17. A system according toclaim 16 wherein the mixer is arranged so no vaporization of thevolatile components of the process stream occurs in the mixer.
 18. Asystem according to claim 16 wherein the mixer is arranged so no morethan about 90% of the volatile components of the process stream vaporizein the mixer.
 19. A system according to claim 15 wherein the vesselincludes internals arranged to separate at least some of the nonvolatilecomponents of the process stream from the heating medium.
 20. A systemaccording to claim 15 further comprising the pump-around loop includinga heater.
 21. A system according to claim 15 further comprising thepump-around loop including a separation device.
 22. A system accordingto claim 15 further comprising a condenser arranged to receive at leasta portion of a vaporized process stream exiting the vapor separationzone of the vessel.
 23. A system according to claim 15 furthercomprising a compressor arranged to receive at least a portion of avaporized process stream exiting the vapor separation zone of the vesseland produce a pressurized vaporized process stream.
 24. A systemaccording to claim 15 further comprising a pre-heater arranged to raisea temperature of the process stream prior to the process stream enteringthe liquid pool zone of the vessel.
 25. A system according to claim 23wherein the pre-heater is arranged to recover heat from a condenserarranged to receive at least a portion of the vaporized process stream.